package cn.com.shxt.base.utils.set;

import java.util.Set;
import java.util.TreeSet;
/**
 * Set operations:
 *  union（并集）, intersection（交集）,
 *  asymetric difference（非对称差集）, symmetric difference（对称差集）, 
 *  is subset（子集）, is superset（超集）
 * @author 憨胖
 *
 */
public class SetUtils {
	public static <T> Set<T> union(Set<T> setA, Set<T> setB) {
		Set<T> tmp = new TreeSet<T>(setA);
		tmp.addAll(setB);
		return tmp;
	}

	public static <T> Set<T> intersection(Set<T> setA, Set<T> setB) {
		Set<T> tmp = new TreeSet<T>();
		for (T x : setA)
			if (setB.contains(x))
				tmp.add(x);
		return tmp;
	}

	public static <T> Set<T> intersection2(Set<T> setA, Set<T> setB) {
		Set<T> tmp = new TreeSet<T>(setA);
		tmp.retainAll(setB);
		return tmp;
	}

	public static <T> Set<T> difference(Set<T> setA, Set<T> setB) {
		Set<T> tmp = new TreeSet<T>(setA);
		tmp.removeAll(setB);
		return tmp;
	}

	public static <T> Set<T> symDifference(Set<T> setA, Set<T> setB) {
		Set<T> tmpA;
		Set<T> tmpB;
		tmpA = union(setA, setB);
		tmpB = intersection(setA, setB);
		return difference(tmpA, tmpB);
	}

	public static <T> boolean isSubset(Set<T> setA, Set<T> setB) {
		return setB.containsAll(setA);
	}

	public static <T> boolean isSuperset(Set<T> setA, Set<T> setB) {
		return setA.containsAll(setB);
	}

	public static void main(String args[]) {
		TreeSet<Character> set1 = new TreeSet<Character>();
		TreeSet<Character> set2 = new TreeSet<Character>();
		set1.add('A');
		set1.add('B');
		set1.add('C');
		set1.add('D');
		set2.add('C');
		set2.add('D');
		set2.add('E');
		set2.add('F');
		System.out.println("set1: " + set1);
		System.out.println("set2: " + set2);
		System.out.println("Union: " + union(set1, set2));
		System.out.println("Intersection: " + intersection(set1, set2));
		System.out.println("Intersection2: " + intersection2(set1, set2));
		System.out.println("Difference (set1 - set2): "
				+ difference(set1, set2));
		System.out
				.println("Symmetric Difference: " + symDifference(set1, set2));
		TreeSet<Character> set3 = new TreeSet<Character>(set1);
		set3.remove('D');
		System.out.println("set3: " + set3);
		System.out.println("Is set1 a subset of set2? " + isSubset(set1, set3));
		System.out.println("Is set1 a superset of set2? "
				+ isSuperset(set1, set3));
		System.out.println("Is set3 a subset of set1? " + isSubset(set3, set1));
		System.out.println("Is set3 a superset of set1? "
				+ isSuperset(set3, set1));
	}
}
